Method for mounting an x-ray marker in an implant

ABSTRACT

A method for connecting an X-ray marker to a base body of an implant is provided. The based body includes a receptacle for receiving an X-ray marker. A flexible film and an X-ray marker are arranged so that at least a section of the film is located between the receptacle and the X-ray marker. The X-ray marker is pressed into the receptacle while interposing the film so that the X-ray marker is plastically deformed and, together with the film, is fixed in a force-fit manner in the receptacle. The film prevents contact between the X-ray marker and the base body.

PRIORITY CLAIM

This application is a 35 U.S.C. 371 US National Phase and claimspriority under 35 U.S.C. § 119, 35 U.S.C. 365(b) and all applicablestatutes and treaties from prior PCT Application PCT/EP2020/066595,which was filed Jun. 16, 2020, which application claimed priority fromEuropean Application Serial Number 19185654.1, which was filed Jul. 11,2019.

FIELD OF THE INVENTION

A field of the invention is X-Ray marker for implants, e.g., stents andvalves. Particular additional example implants include occluders,filters, heart valve prostheses (in particular stent-based aortic valveprostheses) or other vessel support devices

BACKGROUND

In such methods, the X-ray marker has previously been connected to thestent by way of adhesion or pressing, for example.

In the case of adhesion, problems arise that, on the one hand, it isdifficult to precisely meter a comparatively small amount of adhesiveand, on the other hand, the exact positioning of the adhesive amountpresents another challenge. In principle, the problem with adhesion isfurther a limited processing duration (pot life). Moreover, when usingsolvent-based adhesives, it must be ensured that these do not adverselyaffect the implant or the stent.

Furthermore, the problem in the case of pressing is essentially thatfrequently X-ray markers made of noble metals (such as gold or platinum,or the like) are used, which in combination with a base body of thestent made of a base metal create contact erosion. Especially onbiodegradable stents, this can result in an undesirable acceleration ofthe degradation. Additionally, the X-ray marker can work its way out ofthe stent, so that direct contact between the X-ray marker and the basebody has to be prevented. This applies to all joining methods withdirect contact (such as joining by screws, riveting, and the like).

US 2016/0228267 discloses a method for pressing an X-ray marker into astent, wherein a space between the X-ray marker and the stent can befilled with a polymer when the stent is coated.

SUMMARY OF THE INVENTION

Methods of the invention connect an X-ray marker in a simple andreliable manner to an implant in a manner where potential contactcorrosion is to be avoided from the outset. In preferred methods, noadhesive bond needed.

A preferred method for connecting an X-ray marker to a base body of animplant includes providing a base body including a receptacle forreceiving an X-ray marker. A flexible film and an X-ray marker arearranged so that at least a section of the film is located between thereceptacle and the X-ray marker. The X-ray marker and the section of thefilm are pressed into the receptacle, so that the X-ray marker isplastically deformed and, together with the film, is fixed in aforce-fit manner in the receptacle, with the film preventing contactbetween the X-ray marker and the base body.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention and further features and advantages will bedescribed hereafter based on the figures. In the drawings:

FIG. 1A shows a schematic sectional view of a section of a base body ofa stent including a through-opening, a spherical X-ray marker beingarranged above the through-opening, and a film being arranged betweenthe marker and the base body, which is to be pressed into thethrough-opening together with the marker;

FIG. 1B shows a schematic sectional view of the X-ray marker accordingto FIG. 1A, which is arranged in the through-opening of the base bodytogether with a section of the film;

FIG. 2 shows a schematic sectional view of the X-ray marker, the filmand the base body, two pressing jaws being displaced toward one anotherfor pressing the X-ray marker into the through-opening together with thefilm;

FIGS. 3-4 show the plastic deformation of the X-ray marker according toFIG. 2 by the pressing jaws;

FIG. 5 shows the X-ray marker pressed into the through-opening of thebase body, a section of the film protruding from the through-openingafter being pressed in;

FIG. 6 shows a schematic sectional view of the X-ray marker, the filmand the base body after the X-ray marker has been pressed into thethrough-opening of the base body, the section of the film protrudingfrom the through-opening having been removed;

FIG. 7A shows SEM images of a pressed-in X-ray marker made of gold in afilm made of electrospun polyurethane;

FIG. 7B shows SEM images of a pressed-in X-ray marker in fusedpolyurethane in a view from outside the base body;

FIG. 7C shows SEM images of a pressed-in X-ray marker in fusedpolyurethane in a view from inside the base body;

FIGS. 8A-8C show schematic sectional views of the pre-mounting of X-raymarkers on a film over a perforated plate; and

FIGS. 9A-9B show the schematic insertion of the X-ray marker accordingto FIGS. 8A-8C into the through-opening of a base body.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With preferred methods, a connection between the X-ray marker and thebase body of the implant is sufficiently elastic in the process to beable to compensate for a minor deformation of the base body of theimplant. Moreover, the pressing-in operation can advantageously beconfigured in such a way that the wall thickness of the base body is notincreased by the pressed-in X-ray marker.

The receptacle is preferably designed as a cavity, or particularlypreferably as a through-opening.

The base body can include a plurality of mutually connected struts,which form a circumferential lattice structure. Such a base body can beprovided by cutting individual regions out of a tubular blank, forexample by way of a laser. According to a particularly preferredembodiment, the base body is made of a magnesium alloy, and inparticular a Mg—Zn—Ca, Mg—Zn—Al or Mg—Al alloy.

According to one embodiment of the method, it is provided that the X-raymarker is pressed into the cavity or the through-opening, whileinterposing the film, in such a way that the X-ray marker, with acircumferential outer side, makes contact with the film, which, in turn,rests against a circumferential inner side of the cavity or of thethrough-opening, so that a circumferential section of the film isarranged between the X-ray marker and the base body.

Within the scope of the present application, a cavity shall beunderstood to mean any at least one-sided opening in the base body ofthe implant.

According to one embodiment of the method, it is further provided thatthe X-ray marker, after having been pressed into the cavity/thethrough-opening, has a surface that extends along the opening plane ofthe cavity/of the through-opening and is covered by a section of thefilm, which is connected to the circumferential section of the filmwhich is pressed into the through-opening. In other words, the X-raymarker, after having been pressed in, is thus embedded into the film,wherein only a further surface of the X-ray marker, which faces awayfrom the surface covered with the film, is exposed.

According to one embodiment of the method, it is further provided that asection of the film protruding from the cavity/the through-opening iscut off, so that the circumferential section of the film, on one side ofthe base body, preferably ends or is arranged flush with a surface ofthe base body.

According to another embodiment of the method, it is provided that theprotruding section of the film is removed or cut off by way of astamping action during the pressing-in operation. According to analternative embodiment of the method, it is provided that the protrudingsection of the film is removed or cut off, for example by trimming,subsequently for the pressing-in operation.

According to an alternative embodiment of the method according to theinvention, it is provided that the film is dimensioned in such a waythat, after the X-ray marker has been pressed into the base body, thefilm, on one side of the base body, does not protrude from thecavity/the through-opening.

According to one embodiment of the method, it is further provided thatthe X-ray marker is spherical or cylindrical prior to being pressed intothe through-opening. According to one embodiment of the method, it isfurther provided that the X-ray marker, after having been pressed intothe cavity/the through-opening, is half shell-shaped/disk-shaped as aresult of the plastic deformation thereof and, with the two surfacesthereof facing away from one another is preferably designed to be flushwith an adjoining surface of the base body.

Two pressing jaws can be used to press in the X-ray marker, wherein theX-ray marker, together with the film, is arranged between the pressingjaws, and the pressing jaws are moved toward one another for pressingthe X-ray marker and the film into the cavity/the through-opening, sothat the at least one X-ray marker is plastically deformed by thepressing jaws engaging on both sides and, in the process, is fixed in aforce-fit manner in the cavity/the through-opening. According to oneembodiment, the movement of the pressing jaws toward one another can becontrolled in such a way that a final thickness of the at least oneX-ray marker in the pressing direction corresponds to a wall thicknessof the base body (see above).

The film used is preferably designed to be elastically or plasticallydeformable so as to be able to absorb forces that arise when the X-raymarker is being pressed in, without tearing.

According to one embodiment of the method, it is provided that the filmincludes one of the following materials or is made of one of thefollowing materials: a plastic material, a polymer, polyurethane,electrospun plastic, electrospun polyurethane, PTFE, or silicone.

According to one embodiment of the invention, it is further providedthat the X-ray marker is made of a metallic material that is more noblethan a metallic material of which the base body is made. According toone embodiment, the X-ray marker can be made of one of the followingmaterials or can include one of the following materials: a radiopaquemetallic material, gold, a gold alloy, platinum or a platinum alloy.

According to another embodiment of the method, it is provided that thefilm is fused after the at least one X-ray marker has been pressed in,for example so as to round a cut edge of the film, or so as todistribute the material of the film uniformly in an annular gap aroundthe at least one X-ray marker.

According to one embodiment of the invention, it is further providedthat the film is fused as the at least one X-ray marker and the film arebeing pressed into the cavity/the through-opening.

For this purpose, for example, the pressing jaws by way of which the atleast one X-ray marker and the film are pressed into the through-openingcan be heated.

According to another embodiment of the method, it is provided that theX-ray marker, or multiple X-ray markers, and the film are prefabricated.

According to one embodiment of the method, it is provided in this regardthat the flexible film and the X-ray marker are provided, prior to beingpressed in, in that the X-ray marker, along with further X-ray markers,is arranged on a film and suitably fixed there. Thereafter, theindividual X-ray markers can be pressed in.

According to one embodiment, it is provided in this regard that theflexible film and the X-ray marker are provided, prior to being pressedin, in that the film is arranged on a perforated plate including aplurality of holes, wherein the X-ray marker and further X-ray markersare arranged on a respective film section covering a hole and are fixedthere, wherein a curvature is imparted to the respective film section asa result of the hole of the perforated plate arranged therebeneath,wherein a curvature of a film section, including the X-ray marker fixedthereon, is arranged in the at least one through-opening before theX-ray marker is pressed into the cavity/the through-opening of the basebody.

According to another alternative embodiment of the method, it isprovided that the flexible film and the X-ray marker are provided, priorto being pressed in, in that the X-ray marker and further X-ray markersare arranged next to one another and coated with a plastic material,preferably polyurethane, using electrospinning for forming the film.

Electrospinning shall be understood to mean the creation of thin plasticor polymer fibers from a plastic or polymer solution in an electricfield. The solution can be accelerated for this purpose between anelectrode and a counter electrode, wherein the solution is processedinto minute fibers in a complex process, which ultimately deposit on thecounter electrode, with the X-ray markers being able to function as thecounter electrode in the process so that these can be directly coatedwith the film material using electrospinning.

According to another alternative embodiment of the method, it isprovided that the flexible film and the X-ray marker are provided, priorto being pressed in, in that the X-ray marker and further X-ray markersare arranged between two layers of the film forming the film and arefixed to the film.

Another aspect of the present invention relates to an implant, inparticular a stent, including a base body and an X-ray marker that isarranged in a receptacle, in particular a through-opening, of the basebody and connected to the base body by way of the method according tothe invention.

The preferred embodiments are described based on the example of an X-raymarker for a stent, without being limited thereto. The invention is usedto connect a marker to an arbitrary, in particular biodegradable,implant, such as stents, occluders, filters, heart valve prostheses (inparticular stent-based aortic valve prostheses) or other vessel supportdevices.

FIGS. 1A and 1B, in connection with FIGS. 2 to 6, show an embodiment ofa method according to the invention for connecting an X-ray marker 1 toa base body 20 of a stent 2, wherein a base body 20 of a stent 2 isprovided, wherein the base body 20 includes a through-opening 21 forreceiving the X-ray marker 1, and wherein a flexible film and an X-raymarker 1 are provided, so that at least a section 30 of the film 3 islocated between the base body 20 including the through-opening 21 andthe X-ray marker 1, and wherein ultimately the X-ray marker 1 is pressedinto the through-opening 21 of the base body 20, while interposing thefilm 3, so that the X-ray marker 1 is plastically deformed and, togetherwith the film 3, is fixed in a force-fit manner in the through-opening21, wherein the film 3 prevents contact between the X-ray marker 1 andthe base body 20, and thereby precludes contact corrosion.

The invention thus describes an alternative mounting option of X-raymarkers 1 in stents 2. Conventionally, these are glued in using adhesivedosing. Meanwhile, the present invention allows a plastic or polymerconnection to be established between the marker 1 and the base body 20without the dosing of adhesive.

The film 3 used is preferably accordingly elastically deformable anddesigned to be able to absorb forces that arise when the marker 1 isbeing pressed in, without tearing. Electrospun polyurethane, forexample, is one film material that has these properties. In principle,all electrospinnable plastic materials may be used, or also single- ormulti-layer PTFE or silicone films.

According to FIG. 1A, such a film 3 is placed over a base body 20 of thestent 2. The base body 20 and, in particular, the preformedthrough-opening or through-openings 21, which are also referred to asmarker holes or eyelets, are aligned in such a way that a marker 1 canbe positioned in a blind manner from above, which means that theassociated through-opening 21 does not need to be visible through thefilm 3. A film made of electrospun polyurethane is generally not verytransparent. As an alternative, a light source, for example, can beplaced beneath the through-opening 21. The position of the particularthrough-opening 21 then becomes visible from the corresponding shadowthat is cast. Moreover, a counter plunger can be pushed through theparticular through-opening, which then guides the marker 1 during thepressing operation. FIG. 1B shows the X-ray marker 1 arranged in thethrough-opening 21, together with the film 3, prior to the pressing-inoperation, which is illustrated in FIGS. 2 to 4.

Thereafter, the X-ray marker 1, which initially preferably has aspherical shape and can, for example, be made of gold (or another highlyradiopaque and soft metal, such as platinum), is pressed, together withthe film 3, into the through-opening 21 by way of pressing jaws 4. Usinga displacement-controlled movement of the clamping jaws, control isexercised to ensure that the final thickness D of the marker disk 1corresponds to the wall thickness W of the base body 20 of the stent 2.In this way, it can be ensured that the base body is not damaged by thepressing motion, and also that the X-ray marker or markers 1 does not ordo not protrude over the base body edge.

The film 3 can have an appropriate size, so that no protruding filmsection 33 is present after the pressing operation. Otherwise, theprotruding remainder 33 of the film 3 is removed. This can be achievedby a stamping action during pressing or after the pressing-in operation,for example by cutting off the protruding section 33 of the film 3 (seeFIGS. 5 and 6).

According to FIG. 6, the X-ray marker is ultimately preferably pressedinto the through-opening 21, while interposing the film 3, in such a waythat the X-ray marker 1, with a circumferential outer side 1 a, makescontact with the film 3, which, in turn, rests against a circumferentialinner side 21 a of the through-opening 21, so that a circumferentialsection 31 of the film is arranged between the X-ray marker 1 and thebase body 20, or fills a corresponding annular gap between the marker 1and the base body 20.

According to FIG. 6, it is further provided that, after having beenpressed into the through-opening 21, the X-ray marker 1 has a surface 1b that extends along the opening plane of the through-opening 21 andthat is covered by a section 32 of the film 3, which is connected to thecircumferential section 31 of the film 3 that is pressed into thethrough-opening 21.

In addition, the pressed-in film 3 can also subsequently be fused. Thisis done, for example, so as to round a cut edge of the film 3, or so asto evenly distribute the film material (such as the polyurethane) in theannular gap. The fusing can be integrated into the pressing motion, forexample by using heatable pressing jaws 4.

For example, flat nose pliers may be used as pressing jaws, having amechanically limited pressing motion, so that it is not possible topress any further than the wall thickness of the stent. The pressingmotion can also be integrated into the existing process step ofcrimping. Within the scope of the present application, crimping shall beunderstood to mean the process step during which the stent is arrangedaround an expansion element (for example a dilatable balloon of aballoon catheter), and the diameter of the stent is reduced to adiameter for insertion into the body. The stent is compressed onto theballoon.

In an alternative embodiment, which is shown by way of example in FIGS.8A to 9, for example, an assembly is created prior to the actualmounting step, or the step of pressing a marker 1 into an associatedthrough-opening 21 of the base body 20, in which the marker 1 ispre-positioned on the film 3 and, in particular, fixed there.

For example, multiple X-ray markers 1 are pre-mounted on a film 3, forexample in the form of a film strip 3, over a perforated plate (forexample in the form of a perforated metal sheet) (see FIG. 8A), so thata respective X-ray marker 1 is arranged on a film section 34 that coversone hole 50 of the perforated plate 5 and is pressed into the same,whereby a curvature 35 of the film 3 results in each case, whichaccommodates a marker 1 (see FIGS. 8B and 8C).

These curvatures 35 can then be positioned particularly easily, inaccordance with FIGS. 9A and 9B, in the associated through-opening 21 ofthe base body 20, together with the respective X-ray marker 1 arrangedtherein. Thereafter, the pressing operation can be carried out, forexample according to FIGS. 2 to 6 (see above).

Moreover, it is possible to create such an assembly including markers 1and the film 3 by directly coating multiple X-ray markers 1 with asuitable plastic material/polymer (such as polyurethane) by way ofelectrospinning. As an alternative thereto, the option exists to covermultiple X-ray markers 1 on both sides with a film layer (such aspolyurethane), so that the markers 1 are wrapped in a film 3 composed ofat least two film layers.

FIGS. 7A to 7C show SEM images of X-ray markers that were pressed intothe shown stents using the present invention.

The advantages of the present invention are that adhesive dosing (alongwith the attendant drawbacks, see above) can be entirely avoided. It ispossible to use cost-effective X-ray markers in the original state(spherical) since these do not need to have narrow tolerances. Themounting step can furthermore be integrated into the crimping process.

1. A method for connecting an X-ray marker to a base body of an implant,comprising the following steps: providing a base body including areceptacle receiving an X-ray; arranging a flexible film and an X-raymarker so that at least a section of the film is located between thereceptacle and the X-ray marker; and pressing the X-ray marker and thesection of the film into the receptacle, so that the X-ray marker isplastically deformed and, together with the film, is fixed in aforce-fit manner in the receptacle, with the film preventing contactbetween the X-ray marker and the base body.
 2. The method according toclaim 1, wherein the receptacle comprises a cavity or a through-opening.3. The method according to claim 2, wherein the X-ray marker is shapedsuch that a circumferential outer side makes contact with the film,which, in turn, rests against a circumferential inner side of the cavityor of the through-opening so that a circumferential section of the filmis arranged between the X-ray marker and the base body as a result ofthe pressing.
 4. The method according to claim 3, wherein the X-raymarker is shaped, such that after the pressing, a surface of the X-raymarker extends along the opening plane of the cavity or thethrough-opening and is covered by a section of the film, which isconnected to the circumferential section of the film that is pressedinto the cavity or the through-opening.
 5. A method according to claim1, comprising removing, after the pressing, a protruding section of thefilm so that the circumferential section of the film ends flush with asurface of the base body on one side of the base body.
 6. A methodaccording to claim 1, wherein the film is dimensioned such, after thepressing, that the film does not protrude from the cavity or thethrough-opening of the base body on one side of the base body.
 7. Amethod according to claim 1, wherein the X-ray marker is spherical orcylindrical and the pressing deforms it into a half shell or disk shape.8. A method according to claim 1, wherein the pressing is conducted withtwo clamping jaws that engage the X-ray marker and film section on bothsides to deform the X-ray marker a force-fit manner in the cavity or thethrough-opening.
 9. The method according to claim 8, comprisingcontrolling the pressing jaws in such a way that a final thickness (D)of the at least one X-ray marker corresponds to a wall thickness (W) ofthe base body.
 10. A method according to claim 1, wherein the filmcomprises or consists of one of the following materials: a plasticmaterial, a polymer, polyurethane, electrospun plastic, electrospunpolyurethane, PTFE, or silicone.
 11. A method according to claim 1,wherein the X-ray marker is made of a metallic material that is morenoble than a metallic material of which the base body.
 12. A methodaccording to claim 1, wherein the X-ray marker comprises or consists ofone of the following materials: a radiopaque metallic material, gold, agold alloy, platinum, or a platinum alloy.
 13. A method according toclaim 1, comprising fusing the film during or after the pressing. 14.The method according to claim 13, comprising pressing with a heatedelement to conduct the fusing with the pressing.
 15. A method accordingto claim 1, wherein the arranging comprises initially arranging the filmon a perforated plate including a plurality of holes, arranging aplurality of X-ray markers over the plurality of holes and pressing theplurality of X-ray markers with the film and then arranging the filmwith the plurality of X-ray markers over a plurality of receptacles inthe base body and then conducting the pressing.
 16. (canceled)
 17. Themethod of claim 15, comprising coating the plurality of X-ray markers,with a plastic material.
 18. The method of claim 17, wherein the plasticmaterial comprises polyurethane.
 19. The method of claim 15, wherein theinitial arranging comprises arranging the plurality of X-ray markersbetween two layers of the film.
 20. An implant comprising a receptaclefor an X-ray marker in a base body of the implant and a plasticallydeformed X-ray marker force fit into the receptacle with a flexible filmin a manner that the X-ray marker does not contact the base-body.